JP6440451B2 - Load sensing valve device - Google Patents

Description

  The present invention relates to a load sensing valve device that maintains a constant diversion ratio according to the opening degree of each main valve regardless of load pressure fluctuations of a plurality of actuators.

  An apparatus described in Patent Document 1 is conventionally known as this type. This conventional apparatus includes a plurality of main valves and a plurality of compensator valves associated with the main valves. The compensator valve has an axis perpendicular to the spool of the main valve (hereinafter referred to as “main spool”).

The compensator valve is provided with a variable restrictor (hereinafter referred to as “compet restrictor”) in the passage process connecting the main valve and its actuator port on the downstream side of the main valve.
Further, one end of the spool of the compensator valve (hereinafter referred to as “competit spool”) faces the first pressure chamber, and the other end faces the second pressure chamber.

A pressure upstream of the competition restrictor is introduced into the first pressure chamber, and a maximum load pressure of each actuator connected to the plurality of main valves is introduced into the second pressure chamber. ing.
The compensator valve configured as described above controls the opening of the comp restrictor according to the pressures in the first and second pilot chambers, so that the opening of each main valve can be controlled regardless of the load pressure fluctuations of the plurality of actuators. The corresponding diversion ratio is kept constant.

On the other hand, a selection valve is incorporated in the competition spool, and one end of the selection valve faces a maximum load pressure introduction chamber communicating with the second pressure chamber, and the other end is a load pressure introduction chamber formed in the competition spool. To face.
The load pressure introduction chamber is communicated with an actuator port of a main valve associated with the compensator valve via an introduction port formed in the competition spool. However, the opening area of the introduction port is substantially constant regardless of the movement position of the competition spool.

The selection valve configured as described above is configured to guide the pressure of the load pressure introduction chamber to the maximum load pressure introduction chamber when the load pressure led to the load pressure introduction chamber is higher than the pressure of the maximum load pressure introduction chamber. I have to.
The pump regulator operates in accordance with the maximum load pressure introduced into the maximum load pressure introduction chamber, and controls the tilt angle of the variable displacement pump.

JP 2009-204086 A

  In the conventional load sensing valve device as described above, the actuator is connected to the load pressure introduction chamber facing one end of the selection valve via the pressure introduction port having a constant opening degree regardless of the movement position of the competition spool. Since the load pressure is guided, there are the following problems.

For example, when the load pressure of a certain actuator changes from a relatively low state to the maximum load pressure, the responsiveness of the regulator can be improved and the tilt angle of the variable displacement pump can be quickly controlled at the initial stage. desired. This is because, if the control of the tilt angle of the variable displacement pump cannot catch up with the change in the maximum load pressure, the change in the load pressure of the actuator cannot be handled smoothly.
However, if the responsiveness of the regulator is too good even after the initial stage of load fluctuation has passed, the gain of the tilt angle change of the variable displacement pump becomes too large, and the movement of the actuator does not go smoothly as a whole. The problem occurs.

In particular, at the time of inching operation in a boom cylinder or an arm cylinder in a construction machine, if the gain is too large, the movement of each cylinder cannot be performed smoothly.
Therefore, conventionally, it has been required to improve the responsiveness of the regulator at the initial stage of the load fluctuation of the actuator, and to slightly reduce the responsiveness after the initial stage.
However, the conventional apparatus has a problem that such a request cannot be met.

  An object of the present invention is to provide a load sensing valve device capable of improving the responsiveness of the tilt angle control of the variable displacement pump at the initial stage of the load fluctuation and reducing the responsiveness after the initial stage. That is.

  The present invention relates to a device including a plurality of actuators and a main valve connected to each actuator, such as a load sensing valve device of a construction machine, particularly a power shovel.

The main spool and the competition spool are incorporated into the valve body, and the competition spool is perpendicular to the main spool.
Further, the competition spool is provided with a pressure introduction port for guiding the load pressure of the actuator to the maximum load pressure introduction chamber. The pressure introduction port is configured such that the opening area of the pressure introduction port is reduced by a groove formed on the outer peripheral surface of the competition spool.

According to the load sensing valve device of the present invention, the opening degree of the pressure introduction port communicating with the pressure introduction chamber of the selection valve is the initial stage of fluctuation of the maximum load pressure, that is, the initial stage when the competition spool moves to the maximum load pressure introduction chamber side. relatively large in the stage, thus to move to the highest load pressure introducing chamber side, the opening degree of the pressure introduction port is reduced. Therefore, the responsiveness to the tilt angle control unit of the variable displacement pump at the initial stage of the fluctuation of the maximum load pressure is improved, and the subsequent responsiveness can be reduced.

  As described above, in the process of moving the competition spool, the responsiveness to the tilt angle control unit can be changed. Can be controlled smoothly.

It is sectional drawing of embodiment in this invention. It is sectional drawing of the principal part of embodiment in this invention, Comprising: The opening degree of the competition throttle part of the compensator valve | bulb is shown in the state maintained to the maximum.

  In the illustrated embodiment, a main valve V1 and a compensator valve V2 are incorporated in a valve body B. In this way, the valve body B including the main valve V1 and the compensator valve V2 as a set is provided for each of a plurality of actuators (not shown), and usually the valve body B is manifolded.

The valve body B is slidably provided with a main spool MS. Further, a first annular recess 1 is formed around the spool hole for slidably incorporating the main spool MS, and at the center position of the spool hole in the axial direction of the main spool MS.
Further, second and third annular recesses 2 and 3 are formed on both sides of the first annular recess 1, that is, in line-symmetrical positions around the first annular recess 1. Each of the second and third annular recesses 2 and 3 is connected to a variable displacement pump (not shown), and the working fluid discharged from the variable displacement pump is always guided. A path connecting the second and third annular recesses 2 and 3 and the variable displacement pump constitutes an introduction path.

Fourth and fifth annular recesses 4 and 5 are formed on the outer side of the second and third annular recesses 2 and 3 and symmetrically with the first annular recess 1 as the center. Each of the fourth and fifth annular recesses 4 and 5 is always in communication with the flow passages 6 and 7, and load check valves 8 and 9 are provided in the flow passages 6 and 7. The compensator valve V2 is incorporated in the flow path process between the first annular recess 1 and the flow passages 6 and 7.
The load check valves 8 and 9 allow only the flow from the compensator valve V2 to the fourth and fifth annular recesses 4 and 5.

Sixth and seventh annular recesses 10 and 11 are formed on the outer sides of the fourth and fifth annular recesses 4 and 5 and symmetrically with the first annular recess 1 as the center. The sixth and seventh annular recesses 10 and 11 are always in communication with the actuator ports 12 and 13 communicating with the actuator.
Reference numeral 14 in the figure denotes a return passage formed in the valve body B, which communicates with a tank (not shown) and has both end portions positioned outside the sixth and seventh annular recesses 10 and 11.

  On the other hand, the main spool MS is formed with a first annular groove 15 at the center thereof. The first annular groove 15 faces the first annular recess 1 when the main spool MS is in the neutral position shown in the figure. When the main spool MS is switched from the neutral position to either the left or right side, the first annular recess 1 is connected to the second annular recess 2 or the third annular recess forward in the switching direction via the first annular groove 15. Communicate with any of the three. When the first annular recess 1 communicates with either the second or third annular recess 2 or 3 through the first annular groove 15 as described above, the communicating portion constitutes the main throttle portion of the present invention. The main throttle portion has an opening that increases as the main spool MS moves in the switching direction, and decreases as it approaches the neutral position.

  Second and third annular grooves 16 and 17 are formed on both sides of the main spool MS, that is, at symmetrical positions around the first annular groove 15. The second and third annular grooves 16 and 17 correspond to the sixth and seventh annular recesses 10 and 11 when the main spool MS is in the neutral position shown in the drawing. For example, when the main spool MS is switched to the right in the drawing, the sixth annular recess 10 and the fourth annular recess 4 communicate with each other via the second annular groove 16 and the seventh annular recess 11 The return passage 14 communicates with the third annular groove 17.

Further, when the main spool MS is switched to the left side opposite to the above, the seventh annular recess 11 and the fifth annular recess 5 communicate with each other via the third annular groove 17 and the sixth annular recess. The recess 10 and the return passage 14 communicate with each other through the second annular groove 16.
The main spool MS configured as described above has its both ends facing the pilot chambers 18 and 19 and normally maintains the neutral position shown in the figure by the action of the spring force of the centering spring 20 provided in one pilot chamber 19. To do.

  On the other hand, the compensator valve V2 incorporated in the flow path process between the first annular recess 1 and the flow passages 6 and 7 forms a spool hole perpendicular to the spool hole of the main spool MS in the valve body B, A compensator spool CS which is a main element of the compensator valve V2 is slidably provided in the spool hole. In the following, the abbreviation “competit spool” is used for the compensator valve.

The competition spool CS has its axis perpendicular to the axis of the main spool MS, one end thereof faces the pressure chamber 21 that is always in communication with the first annular recess 1, and the other end has the highest load pressure. It faces the introduction room 22. Thus, since the competition spool CS is perpendicular to the axis of the main spool MS, for example, the body of the conventional device disclosed in Patent Document 1 can be used as it is.
Further, the competition spool CS is provided with a competition throttle portion a. The competition throttle portion a has a minimum opening degree relative to the annular recess 23 that allows the flow passages 6 and 7 to communicate with each other in the state shown in FIG. To maintain.

As the competition spool CS moves to the maximum load pressure introduction chamber 22 side, the opening degree of the competition throttle portion a with respect to the recess 23 is increased (see FIG. 2).
Further, the competition spool CS is formed with a pressure introduction port 24 in which the opening degree with respect to the recess 23 is variable according to the movement position. The pressure introduction port 24 forms a groove around the opening on the recess 23 side, and the substantial opening of the pressure introduction port 24 with respect to the recess 23 is reduced in the process of moving the groove relative to the recess 23. I have to.

The recess 23 corresponds to a passage communicating with the actuator side in the present invention.
When the competition spool CS is in the position shown in FIG. 1, the pressure introduction port 24 is kept fully open with respect to the recess 23, and the opening degree relative to the recess 23 is small in the process of moving the competition spool CS upward in the drawing. (See FIG. 2).

The pressure introduction port 24 configured as described above communicates with a pressure introduction chamber 25 formed in the competition spool CS. One end of the selection valve 26 faces the pressure introduction chamber 25, and the other end of the selection valve 26 faces a pressure relay chamber 27 communicating with the maximum load pressure introduction chamber 22.
Therefore, the pressure in the pressure introduction chamber 25, that is, the load pressure of the actuator connected to the main valve V 1 and the maximum load pressure guided to the maximum load pressure introduction chamber 22 act on the selection valve 26.

  At this time, if the load pressure of the actuator connected to the illustrated main valve V1 overcomes the pressure of the maximum load pressure introduction chamber 22, in other words, the load pressure of the actuator is higher than the load pressure of other actuators. If so, the load pressure overcomes the pressure in the maximum load pressure introduction chamber 22, so that the selection valve 26 is opened by the action of the load pressure of the actuator, and the load pressure at that time is led to the maximum load pressure introduction chamber 22. become.

On the other hand, if the load pressure of the actuator is lower than the pressure in the maximum load pressure introduction chamber 22, the selection valve 26 maintains the closed state by the pressure action of the maximum load pressure introduction chamber 22.
Among the load pressures of the actuators connected to the plurality of main valves as described above, the maximum load pressure is selected and introduced into the maximum load pressure introduction chamber 22 of each main valve, and this maximum load pressure is It will be guided to the angle controller.

Next, the operation of this embodiment will be described.
Now, for example, if the main spool MS is switched from the neutral position shown in the figure to the right, the fourth and sixth annular recesses 4 and 10 communicate with each other via the second annular groove 16 of the main spool MS. Communicates with the flow passage 6 of the main valve V1.
Further, since the seventh annular recess 11 and the return passage 14 communicate with each other through the third annular groove 17 of the main spool MS, the other actuator port 13 communicates with the return passage 14.

  At this time, since the first annular recess 1 communicates with the third annular recess 3 via the first annular groove 15 of the main spool MS, the working fluid discharged from the variable displacement pump is supplied to the third annular recess 3 and the first annular recess 3. It is guided to the pressure chamber 21 via the annular recess 1. The pressure of the working fluid flowing into the pressure chamber 21 is lower than the pump discharge pressure by a pressure loss corresponding to the opening of the main throttle portion.

  Since the maximum load pressure of each actuator is introduced into the maximum load pressure introduction chamber 22, the pressure of the pressure chamber 21 acting on one end of the competition spool CS and the maximum load pressure acting on the other end are selected. It will face through the valve 26. The opening degree of the competition throttle portion a is determined by the position of the competition spool CS. The position of the competition spool CS is guided to the pressure chamber 21 facing each other and the maximum load pressure introduction chamber 22. It is determined by the pressure balance with the maximum load pressure.

The working fluid guided to the recess 23 pushes one load check valve 8 open and is guided to one actuator port 12, and is supplied from the actuator port 12 to the actuator. Accordingly, the pressure in the recess 23 becomes the load pressure of the actuator connected to the illustrated main valve V1.
The return fluid of the actuator is returned from the actuator port 13 to the return passage 14 via the third annular groove 17 of the main spool MS.

  On the other hand, the pressure in the recess 23, that is, the load pressure of the actuator is led from the pressure introduction port 24 to the pressure introduction chamber 25, so that the selection valve 26 is led to the pressure in the pressure introduction chamber 25 and the maximum load pressure introduction chamber 22. Compare the maximum load pressure. When the maximum load pressure introduced to the maximum load pressure introduction chamber 22 is higher, the selection valve 26 is kept closed, and the competition spool CS maintains the current state, that is, the previous balance position.

  Further, if the load pressure of the actuator connected to the main valve V1 becomes high with the main valve V1 maintained at the predetermined switching position as described above, the pressure in the pressure chamber 21 also increases accordingly. To do. At this time, the competition spool CS moves upward in the drawing due to the pressure action of the pressure chamber 21 that has risen and the pressure action of the highest load pressure guided to the highest load pressure introduction chamber 22, and the opening of the competition throttle portion a Increase

  If the opening of the competition throttle part a is increased, the pressure loss before and after the competition throttle part a is reduced, so that the differential pressure before and after the main throttle part is kept constant. Thus, if the differential pressure before and after the main throttle portion is kept constant, the flow rate passing through the main throttle portion does not change even if the load pressure of the actuator becomes high. In other words, the diversion ratio according to the opening degrees of the plurality of main valves is kept constant regardless of the load pressure of the actuator connected to the main valves.

  Further, if the load pressure of the actuator connected to the main valve V1 is lowered while the main valve V1 is maintained at the predetermined switching position as described above, the pressure in the pressure chamber 21 also decreases accordingly. To do. At this time, the competition spool CS moves downward in the drawing by the pressure action of the lowered pressure chamber 21 and the pressure action of the highest load pressure guided to the highest load pressure introduction chamber 22, and the opening degree of the competition throttle portion a is increased. Make it smaller.

  If the opening degree of the competition throttle part a decreases, the pressure loss before and after the competition throttle part a increases accordingly, so that the differential pressure before and after the main throttle part is kept constant. Thus, if the differential pressure before and after the main throttle part is kept constant, the flow rate passing through the main throttle part does not change, and the diversion ratio according to the openings of the plurality of main valves as described above is They are kept constant regardless of the load pressure of the actuators connected to these main valves.

The maximum load pressure led to the maximum load pressure introduction chamber 22 is led to the tilt angle control unit (not shown), and the variable displacement pump is connected to the maximum load pressure by the tilt angle control unit. The tilt angle is controlled according to.
Moreover, the pressure introduction port 24 in this embodiment makes the opening degree with respect to the recessed part 23 variable according to the movement position of the competition spool CS.
When the competition spool CS is in the state shown in FIG. 1, since the competition spool CS is fully stroked toward the pressure chamber 21, the load pressure of the actuator connected to the main valve V1 is the load pressure of other actuators. Will be lower.

  When the load pressure of the actuator rises from the above state and the pressure in the pressure chamber 21 overcomes the maximum load pressure guided to the maximum load pressure introduction chamber 22, the competition spool CS is moved upward in FIG. Move to. Thus, in the initial stage where the competition spool CS moves, the pressure introduction port 24 opens to the maximum. Therefore, the tilt angle control unit reacts quickly at the initial stage where the maximum load pressure is reversed.

  When the competition spool CS moves by a predetermined amount, the opening of the pressure introduction port 24 becomes smaller than the recess 23. In other words, since the opening area is reduced during the process of moving the competition spool CS toward the maximum load pressure introduction chamber, the tilt angle control gain of the tilt angle control unit is reduced, and thus stable control is possible. Become.

  In the above-described embodiment, a groove is formed around the pressure introduction port 24, and the substantial opening degree of the pressure introduction port 24 with respect to the depression 23 is reduced in the process of moving the groove relative to the depression 23. Yes. However, instead of the groove, a plurality of small holes may be formed, and the opening of the pressure introduction port 24 may be reduced according to the total opening of these small holes.

  It is most suitable as a load sensing valve device for construction machines, especially power shovels.

B Valve body V1 Main valve V2 Compensator valve 12, 13 Actuator port MS Main spool CS Competition spool a Competition throttle 21 Pressure chamber 22 Maximum load pressure introduction chamber 24 Pressure introduction port 25 Pressure introduction chamber 26 Select valve

Claims (1)

A plurality of valve bodies, each of which is associated with a plurality of actuators and includes an actuator port for guiding a working fluid to the actuators;
A main spool that is slidably incorporated in the valve body;
A competition spool incorporated at right angles to the axial direction of the main spool,
The competition spool is
A pressure chamber into which the working fluid from the variable displacement pump is guided according to the switching of the main spool;
A competition restricting section for varying an opening degree for communicating the pressure chamber and the actuator port according to a moving position;
A pressure introduction chamber on the downstream side of the pressure chamber, to which a load pressure of the actuator is guided
A pressure introduction port communicating the pressure introduction chamber and the actuator port;
A maximum load pressure introduction chamber in which the maximum load pressure of each actuator is guided;
With one end facing the pressure introduction chamber and the other end facing the maximum load pressure introduction chamber, the pressure introduction chamber and a selection valve for selecting a high pressure among the maximum load pressure introduction chamber,
The pressure introduction port, a groove is formed around, in the course of the competition spool is moved to reduce the apertures area of the pressure introduction port by relative movement between a passage in which the groove communicates with the actuator side A load sensing valve device characterized by that.

Images